This invention relates to foot supports, specifically those supports for alleviating pain in feet, especially those which are either malformed, or have misaligned metatarsal heads.
In the normal foot, the anatomical structure is that the body weight is borne, during walking, on the heel and on the heads of the first and fifth metatarsal.
Foot deformities are known for which specific orthopedic shoes or structures have been suggested to correct the various foot and postural deformities which are known to occur. Within these orthopedic shoes it is known to place arch supports, inlays or similar devices, but the construction of these supports is such that they place concentrated forces on additional weight bearing points in the foot, producing undue stresses and strains on the foot's surface and inducing displacement of bones within the foot, often worsening the natural gait of the individual.
Such structures are shown, for instance, in U.S. Pat. No. 4,803,989 to Collins disclosing a form of rigid, hardened metatarsal pad for the specific purposes of raising the heads of the metatarsals over an area. This pad is fixed in size and shape and of a rigid construction formed for a general human foot. The material of the pad is relatively incompressible.
An alternative form of such support is shown in U.S. Pat. No. 3,545,447 to Silverman. Silverman, while recognizing the deleterious effects of a rigid metatarsal arch support, shows a heel stabilizer, a structure cupping the heel to restrain the foot from expanding under load and which raises the heel of the foot, transferring force "evenly" over the heads of the metatarsals.
In these prior art structures, as in others disclosed in the two patents mentioned, there is an assumption that the positioning of the metatarsal has not been deformed by the unsymmetrical loading which gives rise to foot pain. Where, as is more common, foot pain exists because of malforming of the foot or mispositioning of or growths on the various metatarsal heads, such structures only serve to concentrate the weight of the body on to one or more points of the foot, exacerbating rather than alleviating the problem.